1. FIELD OF THE INVENTION
The present invention relates generally to an apparatus and a method for filling and impregnating a plurality of capacitors with a capacitor oil. More particularly, the present invention relates to an apparatus and a method for filling and impregnating a plurality of capacitors with a capacitor oil wherein each of the capacitors includes capacitor elements while a gap between adjacent electrodes is minimized to improve electrical stress.
2. DESCRIPTION OF THE RELATED ART
Hitherto, when capacitors each including capacitor elements with a very small gap between adjacent electrodes are filled with a capacitor oil (electrical insulating oil) while the capacitor oil is sufficiently impregnated in the space between the electrodes, each capacitor is first cleaned, and thereafter, the capacitor is filled with the capacitor oil without any stay of air bubbles in the capacitor.
To facilitate understanding of the present invention, a typical conventional capacitor oil filling/impregnating apparatus will briefly be described below with reference to FIG. 4.
A conventional condensor oil filling/impregnating apparatus 1 as shown in FIG. 4 includes as essential components an impregnating chamber 2 in which a plurality of capacitors a are settled, a capacitor oil storage tank 3 for supplying a capacitor oil therefrom to the impregnating chamber 2, a deaerating column 4, a filter 5 and a clay treating vessel 6. When the respective capacitors a are filled with the capacitor oil, first, the interior of the impregnating chamber 2 is heated by heating means (not shown) while the capacitors a held in an immersing bath 7 are airtightly received in the impregnating chamber 2. Then, the impregnating chamber 2 is evacuated by driving a vacuum pump (not shown) so that the respective capacitors a are dried (for the purpose of removing unnecessary materials from the capacitors a).
After completion of drying, the respective capacitors are cooled for impregnation. And then, a capacitor oil is supplied to the immersing bath 7 from the capacitor oil storage tank 3 so that the condensors a are filled with the capacitor oil while they are immersed in the immersing bath 7. When it is confirmed that a predetermined quantity of capacitor oil is supplied to the immersing tank 7, the capacitor oil supplying operation is interrupted. Then, while the capacitors a are immersed in the immersing bath 7, they are kept still so as to allow each capacitor a, particularly, a spacer (made of a paper or similar material) interposed between adjacent electrodes as a capacitor element to be sufficiently impregnated with the capacitor oil.
On completion of the filling/impregnating operations for the respective capacitors a, a charging/discharging platform (in the form of a wagon) having the immersing bath 7 mounted thereon is displaced outside of the impregnating chamber 2. At this time, a single filling cycle of the capacitor oil filling/impregnating apparatus 1 has been finished. Subsequently, the remaining capacitor oil is recovered from the immersing bath 7 so that the recovered capacitor oil is returned to the clay treating vessel 6 in which it is subjected to refining. The refined condensor oil is then delivered from the clay treating vessel 6 to the oil reserving tank 3 again via the filter 5 and the deaerating column 4 until the oil reserving tank 3 is supplemented with a predetermined quantity of new capacitor oil. In FIG. 4, reference numeral 8 designates a delivery pump.
In addition, a proposal has been made as to a capacitor oil filling/impregnating apparatus as disclosed in an official gazette of Japanese Unexamined Publication Utility Model (Kokai) No. 56-139241. According to this proposal, the apparatus includes an unit for supplying a capacitor oil to each capacitor via an airtightly closed passage which leads to the interior of the capacitor. After the respective capacitors are deaerated and dried in a separate unit arranged independent of the apparatus, they are filled with the capacitor oil in another separate unit. As the filling operation is performed for the respective capacitors, the capacitor oil is properly supplied to them with the aid of a delivery pump and a flow rate adjusting device.
As is apparent from the above description, since the conventional capacitor oil filling/impregnating apparatus is constructed such that respective capacitors are filled and impregnated with a capacitor oil by employing an immersing process to be practiced with the aid of an immersing bath, the capacitor oil flows outside of a case of each capacitor during filling/impregnating operations in an immersed state by a quantity more than a half of the capacitor oil which has been supplied from the capacitor oil storage tank. Since the capacitor oil is expensive, the conventional apparatus includes a recirculating system which is connected to the clay treating vessel, the filter and the deaerating column in order to recover the capacitor oil which has not been filled in the respective capacitors and then reuse it after it is subjected to refining.
However, since a large quantity of capacitor oil is not practically used for the respective capacitors during a filling operation, and moreover, there is a need of enlarging a capacity of each of the clay treating veseel, the filter and the deaerating column for the purpose of removing impurities derived from a refining operation for the capacitor oil recovered from the immersing bath, it is unavoidably necessary that a capacity of each of driving units arranged in the recirculating system is enlarged. Consequently, there arises a problem that the whole capacitor oil filling/impregnating apparatus is constructed in larger dimensions.
In addition, as far as the immersing process is employed for the capacitor oil filling/impregnating apparatus, there arises another problem that all the capacitors are not uniformly filled with the capacitor oil, and moreover, a long time is taken until each capacitor is sufficiently impregnated with the capacitor oil.